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Bulletin No, 9 June, 1920, 


349.658 /y: 3 COMMONWEALTH OF PENNSYLVANIA 


A a 
DEPARTMENT OF .INTERNAL AFFATRS 
James F. Woocward, Secretary 


BUREAU OF TOPOGRAPHIC AND GEOLOGICAL SURVEY 
George H. Ashley, State Geologist 


a eC ee 


FUTURE USE OF RAW COAL 


By 
George H. Ashley 


A very Significant movement of modern industrial life is the 
study now being mace or the vse of coal. The high volatile coals of 
Pennsylvania could be mace tc yield from four to six tires the quan- 
tity “or oil now beings gotten in the State from oil wells. Knowing 
this, are we justified in continuirg to burn raw bituminous coal for 
raising steam, when such method does not utilize the possible by- 
products? At least one autnor has gone So far as to say: "Within 4 
few years it will be against the law to tum bitwninous coal directly; 
it will have to be utilized for its valuabie by-products, worth many 
times what the coal is worth in its raw state, and the thing to be 
burned will be thse coke or residue which is Jeft behind, which after 
all, is greatly superior and more economical. than the raw coal for 
domestic and power Pe nenee si) 


Present use wastetul. |.It has long been recognized that our 
present methods of burning raw coal sre most wasteful. For over 80 
years we made coke in beehive ovens. Then came the by~product oven 
which makes from 7 to 25 at cent more coke from the same quantity 
Poa amon adentlon wyiedesifrom) 7 ito, 15) gallons of tar. and: oil, 
16 to 30 pouncs of sulphate of ammonia, and 6,000 to 7,000 feet of 
gas per ton of coal treated. We have iong known that when used for 
power producticn in the ordinery steam piant driving a’poorly insu- 
favecvenpinel with alow) piston Specd am a slide valve, there is 
delivered only about 4 ver cent of the energy in the coal, Multiple 
expansion engines inventec many yoars age develop about id per cent 
Of the energy, Then came the turdine engine, which obtains nearly 
EG wpericenie) Most of tits loss is(notiin ‘burning the coal but invthe 
engine. As a matter of fact, boiler practice obtains 60 to 75 per 
cent or more of the heating value of the co#1; tke final result 
however is in strong contrast with the use or liquid fuels in 
internal-combustion engines, which reach a relatively high efficiency. 


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Sources of oil, But there is another reason for studying the 
better use of coal, Because of the increasing use of gasoline and 
the rapid depletion of the oil reserves of both the United States 
and Mexico, it will soon become necessary to find additional sources 
of petroleum, Besides the oil obtained from the ground by the drill 
there are two other sources - oi1 shales ine coal. Extensive 
Studies are being made cf the oil shale Ceposits of the country and 
commercial experiments sare in progress looking to their utilization. 
AS yet these experimental plants have not reached commercial pro- 
auction so that their product can compete with petroleum in the 
general market. In the meantime more anc more attention is being 
given to what can be accomplishec with coal, 


Distillation of coal, The usc of coal in meking illuminating 
g2s is a well-known process, anc the burning of coal in beehive ovens 
to make coke has long been preacticec. The introcuction of by- 
procuct coke ovens has been in progress for some years, a progres 
greatly hastened by the war. In all these processes the coal is 
heated to 2 relatively high temperature, 2bout 1800° F. As a result 
of this heating, gas, tar and eammonie bre driven off from the coil, 
ane COKCWAS wictt., in the beehive oven th: gas, tar snd ammonia are 
Jost. In th by-product oven ther are savec except for so much of 
Lue yeas Santis Used in tho process \of),coking. 


It nas long been know} that if coal be heated to 4 mocerately 
high temperature, say 1200 F, the quantity of gas driven off is 
less than at a higher tempe raturo and in place of the usual type of 
tar may be obtained 2 small amount of light oil and usually 2 much 
Jarger amount of heavy oil, The residue is heavier and denser than 
coke, and contains more volatile matter. 


Today experiments on "low temperature distillation of coal” are 
reaching the stage of commercicl production in Englanec, Germeny, anc 
the United States. 


Experiments in the United States, In the United States some 
progress has been made. One company experimcnted for several years 
on by-products from low temperature distillation in 2 plant at 
Irvington, New Jersey, where over i00 American coals were tested. 
Subsequently this’ company built a plant at South Clinchfield, 
VWineimaehavyine a ceaily capacity of 500 tons of..a new Fuel callew 
carbocoal, 


iS crushed and fed continuous-~ 
» The voiratile products 

et coke oven practice, 
iorge 2 semi-coxe product 
that is sof ter Rake ordinary coke, con S38 'to1lO; per cent. volatwic 
matter, burns readily ana could be usec IS Oil hG | a STO G 
Suited to the general merket, The seconc part of the process in- 
volves grinding of this semi-coke, efter which it is mixed with 
pitch, fluxed and briquettec, then carrice to inclined retorts and 
Gistillea for six hours 2t 2 temperature of 16009 F, The retorts 

are about 18 feet long and constructed of aarbcrundum blocks. The 


In the carbocosl process raw coal 
ly by paddles into low temperature ret 
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ends of cast iron are lined with fire brick, Each pe ey is operated 
about one-third full and has a capacity of about one ton an hour, 

The material is advancec by paddles mounted on two parallel 12 inch 
paddie shafts which revolve at 1.8 revolutions per minute. The 
briquettes are dumped and quenched, The by-products from this high 
temperature distillation are treated with the Similar See ie from 
the low temperature distillation. 

One ton of Kentucky’ coal containing 3 per cent’ of moisture, 35 
per ‘cent volatile matter, 55 per cent fixed carbon; and 7 per cent 
ash, is said to yield 1400 pounds of carbocoal, 30 gallong of tar, 
9,000 cubic feet of gas, 20 pounds of ammonium sulphate, and 2 gallons 
of light oil thrown down from the gas, In general, the quantity of 
carbocoal is between 65 and 72 per cent of the weight of coal used, 
The yiele of tar, which is a block oil of petroltum-like fluidity, is 
29 to 42 gallons; and of ammonium sulphate from 20 to 24 pounds per 
ton of coal. The yield of carbocoal is a little higher than the yield 
of coke from the same coal. About four times es much’tar is produced, 
The tar is more valuable as it contains no napthalene, is higher in 
tar acids and cresols than gas tar or coke tar, and contains more 
phenol. After the removal of the phenol this distillate resembles , 
crude petroleum in properties and uses. The amount of ammcinium 
Sulphate yielded is about the same as in making coke. A little less 
g2S 1S produced, but more than enough for the needs of the process, 
The distillation of tar' yields 20 gallons of salable oils of high 
market value; 40 per cent of the tar is tar acid. ‘The. pitch left 
Over is used for briquetting the :semi-coke in the last part of the 
process. This is an amorphous, black residue, less brittle and 
lustrous then high temperature pitches. 


The briquettes are hard, nearly as dense as coal, and those 
derived from coal with 7 per cent ash have a heat value of 13, 000 
B.t.u. The briquettes have little tendency to clinker, are practi- 
cally smokeless, and make a fire that is casily controlled, Tests 
Show these briquettes nearly equal Pocahontas coal in efficiency and 
far excell that coal in “smokeless" character. 


In studying American coals it should be remembered that very 
different results are obtained from the low temperature distillation 
of high volatile coals and low volatile coals. For example, a ton of 
Pittsburgh coal may yield 28 per cent of tar, while a low volatile 
Somerset County coal may yield only 7 per cent of tar, The quantity 
of gas yielded does not differ greatly, though the gas from the low 
volatile coals is much higher in nydrogen and lower in the hydro- 
carbon gases, Thus, gas derived from the Pittsburgh coal may show 
44 per cent hydrogen, and gas from Somersct County coals may snow 
over 60 per cent hydrogen, Again, there is a marked cifference in 
the distillation products of the tar from these several coals, Thus 
Pittsburgh coal may yield 2 per cent of oil when cistilled under 
190, Oy, 38 per cent between 190 anc 300°C., 31 per cent between 
300° ard 3600C, leaving 28 rer: cent of pitch; While Somerset County: 
coal yields no oil below Ve 27 per cent between 190° and 3000C., 
32 per cent between 300° and 360°C., leaving 40 per cent of tar, 

The tar acids from Pittsburgh coal may be double those derived from 
Somerset County coals. The percentage of paraffine from the Somerset 
County coal is slightly less than from Pittsburgh coal. The 


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percentage of ammonium derivatives in Somerset County coal is Bea 
double that from Pittsburgh coal. 


Experiments in_ in ane ten6 . In England the best utilization of 
raw coal has been stud by several companies. Of these the 
Coalite Company eee ln L906 probably is best known. Over 200,000 
tors of coal from all over the world have been treated in England in 
low temperature distillation testis. These and other experiments 
have shown that, from a commercial standpoint, the principal diffi- 

culties are the heating of the coal in a very thin layer and the 
removal of the swollen product.from the retort, The principal 
requirement is that the coal be heated in a layer not more than 
three inches thick. Coal swells on heating and for this reason its 
removal from a cues recor’ 2s ditticult.  itmey ibe. of interest jto 
nots the method devised to meet these difficulties in the production 
or \"Coalite ." In practice "coalite” is made by feeding 2 measured 
quantity of coal from & hopper above into a‘thin vertical retort 
of fire brick, The retorts are 9 feet high, 6 feet 6 inches long, 
and. only ll inches wice insice. But as this width is much too 
great, it is reduced by hanging inside the retort two movable on 
plates. The coal is fed into the space between the chamber walls 
and the pletes, = space only 3 inches wide, leaving the space between 
the plates empty. After the heating of the coal the plates are 
dropped together in the center of the retort, loosening the swollen 
VcCOalitve' ,so that it.can.drop into” a cooling chamber below, If a 
greater thickness of coal is used the inside is not heated high 
enough for the process, or the outside is heated. too high. 


The product’of this process is’a crisp, homogeneous mess, 
smokeless, clean, free from sulphur, having twice the bulk and, when 
burned, radiating nearly douple the heat. of an equal weight of coal, 
It pulverizes easily, is superior to powered coal, and it has been 
Suggested may replace oil as fuel on stezmships. 


Products possible from Feunsylvania coal. Of even greater 
‘interest to the people of Fennsylvania are the by-products of the 


process. It has been: estimated from the results obtained in England 
that by carbonizing 140,000,000 tons of bituminous coal now: mined 

in Pennsylvania more than 400, 900,000 gallons of motor fucl, and 

a OC) 000 ,O00 gallons of Diesel ana lubricating oil could be pro>! 
duced, That woulé be about five times the quantity of oil now being 
produced in: Pennsylvania, In addition there would be recovered 
about 1,050,000 tons of sulphate of ammonin, a fertilizer material, 
The residual material, amounting to about 105 ,000,000 tons, would be 
a smokeless fuel that shoule bring 2 higher price. on the merket 

than the present high volatile coals of the State. 


It may be of interest to translate these figures of production 
into dollars and cents, At 20 cents a gallon, 400 ,000,000 gallons 
of motor oil would yield $80,000,000; at 5 cents A gallon, 

i, 250,000,000 gallons of fuel oil and lubrics ting oil would yield 
£62 | 500 000; at 1 cent 2 pound, 2,100,000,000 pounds of ammonium 
sulphate woula yield $21,000,000, or 2 total for the three of 
$163,500,000. This might ‘be inercased Bu eascite slight advance in the 


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price of the resicual product because of its cleanliness and smoke- 
less cen sch A difference of 50 cents a ton would mean an iri 
creased return of over $50,000,000. In brief, at present prices, 
(May 1922) the by-products of tais process, as they have been 
described, should yield between $150,000, 000-and ‘200,000,000 to 
meet the cost of manufacturing and of the 35 , 000 , 000 tons of coal 
used up in the process. At present prices for coal and gasoline 
this might not prove an attractive return. If the price of coal 
goes down, and the price of gasoline goes up, a time will certainly 
come when the value of the by=procucts will far exceed the cost of 
their production and the market value of the coal used. When that 
times comes raw, high volatile-coal will no longer be burned in 
beehive ovens or under boilers, but will be used only in such plants 
as recover the valunble constituents, 


Revised May 25, 1922. 


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3 0112 077640156 


